Study of the biochemical-genetics of circadian rhythmicity in Neurospora crassa has been undertaken in the hope of discovering the cause of such rhythms in eukaryotic organisms. The ultimate rationale is to study the regulation of selected enzymes and metabolic intermediates to probe for causes of circadian variation in amount or ctivity. During the coming year the principal investigator will be on sabbatical leave in the laboratories of Jerry Feldman and Stuart Brody. During that year the principal investigator will be helping with the assays of cyclic-AMP metabolism and membrane lipid composition. These studies are aimed at determining the role of cyclic-AMP, membrane lipids, mitochondria, and energy charge in the circadian rhythms of normal and mutant (clock and cyclic-AMP) strains of Neurospora. The roles of light, temperature, and chemical inhibitors as they relate to the above types of metabolism are also a major area of interest. Bibliographic references: Hochberg, M.L. and M.L. Sargent. 1974. Rhythms of Enzyme Activity Associated with Circadian Conidiation in Neurospora crassa. J. Bacteriol. 120:1164-1175. Eggerdine, C., J.A. Randall, and M.L. Sargent. 1975. An Altered Invertase in the cot-2 Mutant of Neurospora crassa. J. Gen, Microbiol. 89:102-112.